The people known as “America’s brainiest couple” met over an irregular verb. “It was ‘stridden’,” says Steven Pinker, regarding me steadily from beneath his mop of curly hair. His wife, Rebecca Goldstein, laughs. “Steven cited my use of the word in one of his books,” she explains, “and we started exchanging e-mails about it. You could say that our relationship started with conjugation.”

There could have been no more appropriate way for these two extraordinary minds to meet. Pinker, one of Time magazine’s 100 most influential people, is a renowned cognitive psychologist and the author of bestselling books on popular science. Goldstein, a novelist and philosopher, has received a MacArthur “Genius” Award, a Koret International Award and election to the American Academy of Arts and Sciences. Her new novel, the mischievously titled 36 Arguments for the Existence of God: a Work of Fiction (Goldstein warns me not to leave out the subtitle) is released in the UK this month.

Life chez Goldstein-Pinker involves a stream of intellectual banter, in-jokes and puns. “Ever since I won the Genius Award, the jokes have been endless,” Goldstein says. “Whenever I burn the dinner Steve playfully mentions it.”

Not that they are prone to antagonism. “We’ve never had a disagreement, and that’s an absolute truth,” says the philosopher. “We have code phrases for everything that only the two of us understand.” Can she share any? She thinks for a moment. “Do you know?” she says. “My mind’s gone completely blank.”

The couple are not without their personal eccentricities — she is an insomniac, he is obsessed with gadgets — but over the years they have grown increasingly symbiotic. “It is no accident that my latest book, The Stuff of Thought, incorporates philosophy,” Pinker explains. Likewise, Goldstein finds his input invaluable. “I used to be very private about my writing,” she says, “but now I can’t imagine how I wrote anything without Steven’s feedback.” It suddenly seems a little less strange to be interviewing two people about one novel.

Goldstein’s 36 Arguments is a philosopher’s novel about atheism and spirituality. Set in the world of American academia, it centres on Cass Seltzer, a psychologist of religion who “has a fundamental niceness written all over him”. Seltzer has become a celebrity through the unexpected success of his book on atheism,The Varieties of Religious Illusion, the title of which is a nod to William James and Sigmund Freud — one of the subtle and not-so-subtle digs at the excesses of academia that stipple the book.

Seltzer is no Richard Dawkins. Despite his atheism he is subject to the religious impulse, experiencing an “expansion out into the world, which is a kind of love, a love for the whole of existence”, and having the sense that “the Universe is personal, there is something personal that grounds existence and order and value and purpose and meaning”.

Dubbed “the atheist with a soul” by the media, Seltzer has been suddenly granted wealth, fame, a beautiful girlfriend and a lucrative offer from Harvard. And he is “grateful” to the Universe in a spiritual, if not religious, sense.

Through a corkscrewing narrative the novel embarks on a retrospective of Seltzer’s journey, featuring a professor- guru by the name of Jonas Elijah Klapper (a “Jewish walrus” with a messiah complex); two previous romantic interests and a trip into the heart of Jewish spirituality by way of a fictional Orthodox congregation nicknamed “America’s only shtetl” (a small town).

All of this adds up to a world view that seems inconsistent. While atheism is clearly being promoted — an appendix attempts to debunk the existence of God in 36 pithy refutations — the novel is nevertheless imbued with the full richness of human spiritual experience. “I wrote the book because I felt something was missing from Dawkins and the New Atheists,” Goldstein says. “Of course, I agree with them philosophically. But their raging debate takes place purely on the intellectual plane. They just don’t know how spirituality feels from the inside. Religious world views go deep down, they are so vital and sensual. Only a novel could get at that. Even Steven felt more of what it would be like to have a spiritual experience after reading my novel.”

Pinker nods bashfully and smiles. “There is no such thing as different types of atheism,” he points out. “If you don’t believe in God, that’s an absolute position. “We’re both atheists,” Pinker says, “ it’s just that Rebecca has a better phenomenological understanding of the spiritual experience.”

This is connected to her Orthodox Jewish upbringing. “My father was a cantor,” she says, “and as a teenager I was sent to an incredibly right-wing religious school. I used to play truant and sneak off to the library to read philosophy. By the time I was 15 I no longer believed in God.” Although she found religion “stifling”, it also gave her a “deep sense of value for the transcendent experience”.

The key figure in Goldstein’s philosophical evolution was the 17th-century Jewish philosopher Baruch Spinoza — the subject of her 2006 book Betraying Spinoza — who in 1656 was excommunicated for his beliefs. “His spirit hovers over the novel,” she says. “He was the main inspiration behind it.”

She was introduced to the philosopher at school. “My teachers saw Spinoza as a heretic,” she recalls. “He denied the concept of a personal, creator God whose purpose infiltrates reality. Instead, he identified God with the laws of nature. I felt an affinity with this pantheistic approach.”

Spinoza is often seen as a proto-atheist. According to Goldstein he offers spiritualised secularism. “He wants us to seek an experience of awe and transcendence through striving passionately to understand the laws of nature, in all their intricacy,” she says. “To be in a state of expansive understanding is to experience a very powerful emotion, very loving and grateful. Both transcendent emotion and the grounds for morality are included in this secular context — both a largeness of spirit and a thoroughgoing, ethical way of life.”

Goldstein’s novel, with its emphasis on reconciling the intellectual rigour of New Atheism with a thirst for transcendence, is a thoroughly Spinozan project. “Spinoza is the great reconciler of things that seem to be polar opposites,” she says. “Mind and body, reason and spirituality. Maybe that’s a deeper sense in which Spinoza’s spirit hovers over the novel.”

“From my point of view I have a degree of respect for religious experience, and a fondness for Judaism,” Pinker says. “But I find it difficult to relate to these spiritual epiphanies. As a scientist I have every reason to believe that they arise from information-processing activity in the brain, not the spark of a soul.”

Be that as it may, it is refreshing to hear an atheist academic speak in such terms. As I say goodbye to America’s brainiest couple I can’t help wondering if Goldstein’s novel might just represent a first small step into a post-New-Atheist world.

36 Arguments for the Existence of God: A Work of Fiction, by Rebecca Goldstein, Atlantic Books (£12.99; offer price £11.69)